In actual production, physiological diseases and infectious diseases of crops are often confusing. If they are misdiagnosed, they may delay the best prevention and treatment time and cause irreversible losses. Or abuse of pesticides, affecting the quality of agricultural products, causing damage to humans and animals, causing environmental pollution. Therefore, accurate and timely diagnosis and appraisal are the prerequisites and guarantees for the prevention and control of plant diseases.
Physiological diseases "three sexes and no"
Physiological diseases of plants are caused by non-biological factors, ie unfavorable environmental conditions. These diseases are not infected by pathogens and cannot be transmitted among plant individuals. Therefore, they are also called non-infectious diseases.
In the occurrence and development of sudden disease, the majority of the time of onset is more consistent and often occurs suddenly. The shape, size and color of lesions are relatively fixed.
The generality is usually formed into pieces and blocks. It is often related to special conditions such as temperature, humidity, light, soil quality, water, fertilizer, waste gas, waste liquid, etc. Therefore, there is no disease center, and the disease condition of adjacent plants is not very different. Some different crops or weeds nearby also show similar symptoms.
Sporadic majority is the whole plant disease, and the distribution of different plants on a regular basis, if you take appropriate measures to change the environmental conditions, plants can generally restore health. Disease-free physical symptoms only have symptoms and no symptoms.
Infectious diseases "Three sexes have one"
Infectious diseases are caused by biological factors and can be transmitted to each other among plant individuals. Therefore, they are also called infectious diseases.
Sequential disease has a light, medium, and severe degree of change in its occurrence and development. The shape, size, and color of lesions change at the beginning, middle, and later stages. Therefore, lesions at various stages can be seen in the field at the same time.
There is a disease center in the limited field, that is, there is a first sporadic diseased or diseased leaf in the field, and then spreads to the surrounding area. Diseases and plants will staggered, and the disease status of plants farther from the disease center will be reduced. There are also differences in the condition of the neighboring strains.
In addition to viruses, nematodes, and a few fungi and bacterial diseases, the distribution of lesions in various parts of the same plant is not regular, and the occurrence of lesions is random.
Diseases that are contaminated with viruses and bacteriophage have other signs of disease. For example, bacterial diseases have pus in the diseased part, and fungal diseases have rust, powdery material, moldy material, and cotton wool in the diseased part.
Of course, no matter whether it is a physiological disease or an infectious disease, in order to be more accurate in diagnosis and identification, on the basis of the above-mentioned diagnosis, it is necessary to combine the laboratory identification in order to further obtain more accurate identification results.
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